Thousands of Iranian drones have yet to be destroyed

They could be producing thousands per day, so that statement is absolutely worthless.

Man-portable air defense systems (MANPADS) would not have been destroyed. However, the F-15 would probably have flown outside their range but not the A-10.

Launchers is one thing, but how about number of missiles to launch? It seems like they're only launching around 20/day. And they're mostly intercepted.

Absolutely unsurprising. Iran has had literal decades to prepare for this fight. It's a big mountainous country, and they are arguably the most experienced tunnel builders in the world. If US intelligence says they still have half of their missile launchers, I would bet they have a lot more than that. They have also been watching and learning from the war in Ukraine, something the US has apparently failed to do.